7.4 to 8.1 upgrade

[osewblue]

I have a 1996 gmc Suburban with a 7.4 vortec and because of high milage it is getting a little winded. Recently I have come across a 2000 8.1 in need of rebuilding. I know the 8.1 should bolt in the place of the 7.4 but what other changes are needed to complete the swap, will the computer work or will it need to be reflashed? will the fuel injection work or not? and what other issues may be encountered to complete this swap?

[Colorado Kid]

The 8.1L and 7.4L have less in common that you may have been led to believe. The firing order, for instance, is different. Therefore the computers are not interchangable. The fuel injection systems are completely different. The front covers are different which may mean that none of the accesories will bolt up.

 

This swap isn't impossible, but it will be more difficult even than swapping a 6.5TD or a small-block into your truck becasue at least those engines were available in similar trucks, so the misc. parts exist. Rebuilding the 454 you have (or another one like it, to save downtime) is a far simpler job.